1. Field of the Invention
The invention relates to an aerosol space spray containing ultra high concentrations of active ingredients.
Throughout this specification the term "space spray" will be used to define aerosol formulations used for dispersion of an active ingredient in the air as opposed to aerosol formulations which are used to apply an active ingredient to a surface, e.g. antiperspirants, polishes, surface disinfectants etc.
2. Description of the Prior Art
Aerosol formulations have been known for at least 50 years in the art of aerial dispersion of insecticides, air fresheners and other active ingredients.
Conventionally, to obtain the desired characteristics of an aerosol for dispersion into the air or otherwise, the formulations contain minimal active ingredients, a solvent for the active ingredient and a suitable propellant. The active ingredient usually constitutes less than 1% w/w. The solvent is present in the order of 10-20% w/w and the propellant constitutes 80-90% w/w. In most cases of such aerosol formulations, the solvent is a hydrocarbon solvent and the propellant a fluorocarbon or hydrocarbon. Alternatively, the propellant is partially substituted with water, wherein the weight percentage being water is in the range of 30-40% w/w. Therefore it is evident that to deliver one gram of insecticide conventionally requires the release to the atmosphere of between 80 and 250 g of volatile organic compounds (VOC's). Volatile organic compound (VOC) is the general name given for compounds with an appreciable vapour pressure, for example, fluorocarbons, hydrocarbons i.e. kerosene, butane etc. commonly used as propellants.
In surface applications dispersal of the active ingredient of the aerosol over a large area is not vital to the efficacy of the formulation. In many surface sprays it is also important that the active ingredient contact the surface in high concentrations and often for a lengthy period of time - this is particularly important in the case of disinfectants. Accordingly, and in general, aerosol surface sprays containing high amounts of active ingredient are known.
CA 1106329 (BRISTOL-MYERS COMPANY) discloses an antiperspirant formulation comprising about 20-50% w/w of a solid antiperspirant material suspended in about 20-50% w/w of an appropriate oil. About 20-50% w/w of an appropriate propellant is also present in addition to a suspending agent and other adjuvants. In this formulation, the solid active ingredient is suspended in the oil which in turn is suspended throughout the propellant.
Another type of aerosol surface spray is disclosed in JP 78044494 ((TOKA-) TOKYO AEROSOL KAGAKU KAISHA) wherein 65-85 vol % of raw paint liquid, 35-15 vol % of a propellant and a solvent containing not less than 55 vol % (with respect to the paint) of acetone are combined together. The paint is solubilised by the solvent and in turn dissolved in the propellant.
An attempt to increase the amount of powdered solid active ingredient in an aerosol composition was described in AU 512912. In the formulation described at least 15% powdered solid active ingredient is dispersed in an emulsion of water and an anhydrous carrier. Added to this dispersion is then an anhydrous condensed hydrocarbon aerosol propellant gas miscible with the anhydrous carrier so that a final emulsion in which the active ingredient is dispersed is formed. It will be understood that, as in the prior art outlined hereinabove, the active ingredient in this formulation is dispersed or dissolved throughout the propellant. A stated result of this composition is that smaller amounts of propellant gas are required than is conventional for aerosols of this type.
AU 594736 (CHURCH & DWIGHT CO. INC.) discloses an air deodorizer comprising an aerosol having as the dispersed phase, liquid droplets comprising 2-25% of a deodorizing agent. Fragrance may also be included in the deodorizer in an amount of up to 3% by weight of the solution. A propellant in an amount of 8-40% by weight of the resulting aerosol spray may be present as a means for dispersion of the deodoriser.
In a formulation described in AU-B-58959/80 a novel hydrogenated hydrocarbon is described for use as a solvent in aerosol sprays. More particularly 10-89.5% of halogenated hydrocarbon as solvent is claimed in conjunction with 10-70% of liquified aerosol propellant and 0-75% of other organic solvents. Again it is clear that it is the function of the hydrocarbon and other solvents in this formulation to act as solvents of the active ingredient which is present in comparatively small amounts.
According to the prior art, especially in relation to insecticides, in order to solvate pyrethrins and synthetic pyrethroids and other insecticides sufficiently to provide break up energy to fully atomise the insecticide into fine atomised particle dispersions, it is clear that large amounts of propellant and solvents are required in proportion to the active ingredient.
It is apparent that with a general trend around the world for manufacturers and producers to be more environmentally aware as a result of, primarily, Government constraints and consumer demand, there is a real need to reduce the fluorocarbons, hydrocarbons and other VOC's released into the atmosphere since it is thought that they contribute significantly to atmospheric pollution.
Much research has been performed in search of finding a substitute propellant for the conventional fluorocarbon and hydrocarbon propellants for example, by the substitution of water for some of the hydrocarbons; however, a comparative substitute is yet to be found. By way of the water substitute example, water based aerosols do function to disperse the active ingredient but generally not in sufficiently fine enough drops for adequate air dispersal.
Accordingly it is an object of this invention to ameliorate at least some of the disadvantages of the prior art.
More particularly, it is an object of this invention to achieve an improved aerosol space spray which requires less release of undesirable VOC's into the environment. Most desirably, it is another object of the invention to substantially reduce the amount of VOC's required in an aerosol space spray.